7, 7-di(fluoroalkyl)-1, 3, 5-cycloheptatrienes and 2, 2-bis(fluoroalkyl)-bicyclo[3.2.0]-3, 6-heptadienes



United States Patent 3,391,202 7,7 DI(FLUOROALKYL) 1,3,5 CYCLOHEPTA-TRIENES AND 2,2 BIS(FLUOROALKYL) BI- CYCLO[3.2.0]-3,6-HEPTADIENES DavidM. Gale, Wilmington, Del., assignor to E. I. du Pont de Nemours andCompany, Wilmington, Del., a corporation of Delaware No Drawing. FiledJan. 12, 1966, Ser. No. 520,100 4 Claims. (Cl. 260-648) ABSTRACT OF THEDISCLOSURE Novel 7,7-di(fiuoroalkyl)-l,3,5-cycloheptatrienes and 2,2bis(fluoroalkyl)bicyclo[3.2.0] 3,6-heptadienes are prepared. The2,2-bis(fluoroalkyl)bicyclo[3.2.0]-3,6-heptadienes are formed by thereaction of bis(fluor0alkyl)- diazomethane and an aromatic compoundirradiated with actinic radiation at temperatures of 50 to 75 C. and the1,3,5-cycloheptatrienes are formed by heating the reaction mixture at atemperature of 100-300 C. The 1,3,5- cycloheptatrienes are useful assolvents for waterproof coatings and both classes of the compounds areuseful as silicone oil gelling agents.

This invention relates to perfluoroalkyl substituted1,3,5-cycloheptatrienes and perfluoroalkyl substitutedbicycle-[3.2.0]-3,6-heptadienes and to the processes for theirpreparation.

More specifically, this invention relates to 7,7-bis(fluorinatedalkyl)-1,3,5-cycloheptatriene represented by Formula I, and2,2-bis(fluorinated alkyl) bicyclo[3.2.0]-3,6 heptadiene represented byFormula 11 I II wherein R and R taken separately can be the same ordifferent and represent perfluoroalkyl, w-hydroperfluoroalkyl orw-chloroperfluoroalkyl wherein said alkyl groups contain 1 to 8 carbonatoms and R is a member selected from the class consisting of hydrogen,chlorine and alkyl containing 1 to 6 carbon atoms.

It has been found that the 1,3,5-cycloheptatrienes of this invention areformed by the reaction of bis(perfluorinated alkyl)diazomethane witharomatic and substituted aromatic hydrocarbons at temperatures of 100 to300 C. It has further been found that a mixture of the 7,7-bis(perfiuoroalkyl)-l,3,5-cycloheptatriene and 2,2- bis (perfluoro alkyl)bicyclo[3.2.0] 3,6 heptadiene are formed when a mixture of his(perfluorinated alkyl)diazomethane and an aromatic compound isirradiated with actinic radiation at temperatures of 50 to 75 C.

The compounds of this invention are interconvertible. Thus,1,3,5-cycloheptatrienes (I) can be converted photolytically intobicyclo[3.2.0] -3,6-heptadienes (II) by means of actinic radiation andbicyclo[3.2.0]-3,6-heptadienes (II) can be thermally converted intoperfluoroalkyl substituted 1,3,5-cycloheptatrienes (I). Thisinterconversion is illustrated by the following equation.

ice

The thermal reaction (A) is carried out at temperatures of 100-300 C.with temperatures of ISO-250 C. usually employed. The photolyticreaction (hv) is carried out by the use of actinic radiation for 10 to100 hours at temperatures of C. to C. The actinic radiation used for theinterconversion is that which is capable of causing diazomethanes toevolve nitrogen. Radiation of this type emanates from commerciallyavailable ultraviolet light sources.

It is believed that the reaction of the diazomethane and aromaticcompounds occurs by the addition of the carbene [R R C:] which isproduced by the decomposition of diazomethanes. Nitrogen is formed as aproduct of the decomposition. The addition of the carbene to thearomatic compound can occur at any of the aromatic double bonds.Therefore, a mixture of position isomeric products is obtained when thereaction is conducted with substituted aromatic compounds. The mixtureconsists of substituted 7,7 (fluorinated alkyl) 1,3,5-cycloheptatrieneswherein the substituent is found at all but the 7-position. Likewise,the isomerization of a substituted 7,7-(fluorinatedalkyl)-1,3,5-cycloheptatrienes produces a mixture of substituted2,2-(fluorinated alkyl)-bicyclo[3.2.0]-3,6- heptadienes wherein thesubstituent is found at all but the 2-position.

The compounds of this invention are produced by mixing the desiredaromatic compound and diazomethane together in any proportion (althougha l to 50 molar excess of aromatic is usually employed) and irradiatingthe mixture with actinic radiation which causes the diazo compound toevolve nitrogen (such radiation emanates from common ultraviolet lightsources) at a temperature of 80 to 100 C. The 1,3,5-cycloheptatrienesare produced by heating the bicycloheptadienes or mixtures of thebicycloheptadienes and cycloheptatrienes at a temperature greater than100 0., however, a temperature of to 200 C. is usually used. The thermaland photolytic steps may be combined in any order depending on whichproducts are most desired. The photolysis as the sole or major (usuallylast and for longer durations) step gives good yields ofbicyclo[3.2.0]-3,6-heptadiene While thermolysis as the sole or majorstep gives good yields of 1,3,5cycloheptatrienes.

The products are isolated by ordinary means, for example, bydistillation. Time and pressure required to effect the reaction are notcritical. The time and pressure used is determined by taking intoconsideration the stability of the reactants and products. It ispreferred that the photolytic process be carried out at atmosphericpressure for the time necessary for the diazomethane compound to evolveone equivalent of nitrogen gas, generally 24 to 96 hours, and that thethermal process be carried out in an autoclave at autogenous pressuregenerally for 8 to 24 hours. An inert solvent such as1,1,2-trichloroethane can be employed as a reaction medium.

The aromatic moiety of the above reaction can be benzene and substitutedaromatic compounds, such a; toluene, ethylbenzene, cumene, butylbenzene,hexylbenzene, and chlorobenzene.

The bis(fiuorinated alky1)-, bis(w-haloperfluorinated alkyl)- andbis(w-hydroperfluorinated a1ky1)diazomethanes used in the processes ofthis invention are represented by the formula R R CN wherein R :and Rare fluorinated alkyl or alkylene groups described above. Examples ofthese diazomethanes are: bis(l,1,2,2-tetrafiuoroethyl)- diazomethane,bis(2-chloro-1,l,2,2,-tetrafluoroethyl) diazomethane,bis(trifluoromethyl)diazomethane, bis (pentafluoroethyl)di-azomethane,chlorodifluoromethyltridecafiuorohexyldiazomethane, andbis(chlorodifluoromethyl)diazomethane.

The diazomethane compounds used herein can be prepared by oxidation ofthe corresponding hydrazones. preterably with lead tetraacetate in acarbonitrile solvent as described in the copending application of CarlG. Krespan and William I. Middleton, Serial No. 459,120. tiled May 26,1965, now Patent No. 3,242,166.

In order that the invention may be better understood. the followingdetailed examples are given.

A 4.8 ml. (6.5 g.) sample of bis(trifiuoromethyl)diazo- 1 methane wasdistilled into 50 ml. of dry benzene in a .340 ml. Hastelloy tube andheated at 200 C. for 8 hours. The recovered colorless solution (46 g.)was shown to contain, in addition to a large volume of benzene. at leasttwo products (by gas chromatographic analysis on a silicone greasecolumn at 67 C.). Distillation gave 6.05 g. (70%) of product, B.P.132-141 C. Upon fractionation, a fraction was obtained, B.P. 141 G,1.4062, in about 62% yield which was shown to be 7,7-bisttrifiuoromethyl)-1,3,5-cycloheptatriene by spectral data and analysis.An essentially pure sample of the 1.3.5-cycloheptatriene was obtained byfractionation.

Spectral data or" 7,7-bis(trifluoromethyl)- 1,3,5-cycloheptatrieneInfrared absorption: peaks 3045 cm.- =CH) and no peak corresponding toCI-I and CF aosorptlon. Ultraviolet absorption: A =276 ts=3.200).

Mass spectrum: parent peak at m/e-228 and required m 05% that,

A 4.0-ml. (5.6 g.) sample of bis(trifiuoromethyl)-diazomethane wasphotolyzed for hours with a H85A3 lamp through Pyrex in the presence of40 ml. of dry benzene. The temperature of the reaction mixture wasmaintained at 25 C. or less. The product (2 g.) was isolated bydistillation. This product was separated using a preparative gaschromatograph and identified as 2,2-bis(trifluoromethyl)-bicyclo[3.2.0]3,6 heptadiene, and 40% 7,7-bis(trifluoromethyl)-1,3,5-cycloheptatnene.

The bicyclo[3.2.0]-3,6-heptadiene, B.P. 139 C.. was rdencolumn of TableI are obtained.

tified by the following analysis and spectral data.

Spectral data for lit; as 11..

liuitfrared absorption: peaks 1565 cm. (cyclobutene); 11518 cm.lcyclopentene); 3180 and 3080 cm.-

H); .2950 cm. (sat. CH).

l traviolet absorption: maximum extinction coefiicient was less than 30.

llllass spectrum: parent peak at 228 and fragments. Proton magnetic:1-=3.58 (Ha), 3.95 (Hb), Jab=2.5 1.1. s.: -,-=o.12 (He), 6.27 (Hd),Jcd=0 c.p.s.; :3.58 (He), 4.48 (Hf), Jef=6 c.p.s.

Ba and Hb were decoupled to solve the difficulty caused by the overlapof Ha and He; when Hb was decoupled from Ha. it changed from two linesto one. All other I- values were close to zero. F NMR: a pair ofquartets ljjl=9.5) at and +336 c.p.s. from external the low fieldquartet split further.

lnalvrzs-Calcd for C H F (228.14): C, 47.39; H,

; F, 49.98. Found: C, 47.77; H, 2.92; F, 50.66.

llEXAMPLE III CF: CFa

The above interconversion was demonstrated directly. The diene gaveconversion to the 1,3,5-cyclolteptatriene when heated to 225 C. for 5hours and 89% conversion when heated at 225 C. for 12 hours.

l.,3,5-cycloheptatriene gave 10% conversion to thebicyclo[3.2.0]heptadiene in 16 hours and 97% converlion in 72 hours whenirradiated with a GE. HA3 lump. Products were identified by gaschromatographic retention times and infrared analysis.

.1. mixture or 45 ml. of benzene and 2.8 ml. (4.7 g.) intbistpentatluoroethyl)diazomethane was heated in a llastelloy tube at 150C. for 8 hours. Distillation gave 1.3 RP. 42 C./5 mm. Hg, "1325 1.3886,of 7,7-bis pentafiuoroethyl)-1,3,5-cycloheptatriene. The H NMR spectrumshowed a multiplet at 3.67 (area 4) and at =45 area 2). The F NMRindicated a multiplet at +613 {area 3) and +2884 (area 2) c.p.s. fromexternal CCl FCCl F.

.. irzal yszs.Calcd for C H F C, 40.25; H, 1.83;

57.90. Found: C, 39.87; H, 2.09; F, 57.83.

When the diazomethanes and aromatic compounds of liable I are reactedaccording to the procedure of Example l or Example II, the products inthe right-hand .lBLE I Diazomethane romatic inaction Product (s)Compound "brnpound unditions (1)ChlOl'OdlfiuOfOmBthyl'w'hydl'operfluoro' Hcxylbcnzene Example IChlOlOldfillolomethyl)-7-(whydroperfluoropentyD-hexylpentyl-diazomethane..lihb-cycloheptatnene. I (2) Chlorodifluoromethyl-tridecafiuorohexyl-.;hlorobenzene Juample II corodifluoromethyD-7-(tndecafluorohexyl)-chlorodiazomcthane. 11,5cyeloheptatiiene and 2-(chlorodifluoromethyl)-2-tdecafluolohexyl)cl1lorobieyclol3 2 0]-3,6-heptad1ene (3)2-chloro-1,1,2,2-totra-fiu0r0etl1yltrilluoro- Benzene -Aumplc II.micro-1,1,2,ZtetrafluQro-ethy1)-7-(trifluoromethyl)- *elobeptatriene and24 2-ch1oro-1,1,2,2-tetrafiu0ro methyl-diazoinethane.

The 1,3,5-cycloheptatrienes of this invention are useful as solvents forwater-proof coatings. The following example illustrates this use.

EXAMPLE V A sample of polytetrafiuoroethylene wax (MP. ca. 83-145 C.)was dissolved in 7,7-bis(trifluoromethyl)- 1,3,5-cycloheptatriene. Theresulting solution was poured onto a piece of untreated filter paper.The solvent was removed with a warm air stream. The coated portion ofthe paper was water repellent when placed in water. The uncoated portionwas not water repellent and wetted immediately.

The compounds of this invention are useful as silicone gelling agents.The following example illustrates this use.

EXAMPLE VI To a 50-ml. sample of GE SF-96 (100) silicone fluid heated at230 C. was added a 3 mg. mixture of 70%7,7-bis(trifiuoromethyl)-1,3,5-cycloheptatrien30% 2,2- bistrifiuoromethyl) bicyclo 3 .2.0] -3,6-heptadiene. Heating was continuedfor hours. The silicone oil gelled on cooling. The silicone fluid heatedalone for 10 hours at 230 C. was not gelled on cooling.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed since obviou modifications will occur to those skilled in theart.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Compounds selected from the group consisting of wherein R and R takenseparately can be the same or different and each representsperfluoroalkyl, w-hydroperfluoroalkyl or w-chloroperfiuoroalkyl whereinsaid alkyl groups contain 1 to 8 carbon atoms and R is a member selectedfrom the class consisting of hydrogen, chlorine and alkyl containing 1to 6 carbon atoms.

2. Compounds of claim 1 wherein R and R are trifluoromethyl and R ishydrogen, said compounds being7,7-bis(trifluoromethyl)-1,3,5-cycl0heptatriene and 2,2-bis(trifiuoromethyl(bicyclo [3.2.0] -3,6-heptadiene.

3. Compounds of claim 1 wherein R and R are perfiuoroalkyl groupscontaining 1 to 8 carbon atoms.

4. The compound of claim 1 of the formula wherein R and R arepentafiuoroethyl and R is hydrogen; said compound being7,7-bis(pentafluoroethyl)l,3,5- cycloheptatriene.

References Cited Kirmse, Carbene Chemistry, pp. 34 and 35 (1964).

Srinivasan, J. Am. Chem. Soc., pp. 3432 to 3436 (1962).

Gale et al., J. Am. Chem. Soc., vol. 87, p. 657 (1965).

Muller et al., Tetrahedron Letters, vol. 22, p. 1501 (1963).

BERNARD HELFIN, Acting Primary Examiner.

LEON ZITVER, Examiner.

M. JACOB, Assistant Examiner.

